Immunological and clinical factors associated with adverse systemic reactions during the build-up phase of honeybee venom immunotherapy

Summary Background Adverse systemic reactions (SRs) are more common in honeybee venom immunotherapy (VIT) than in wasp VIT. Factors that might be associated with SRs during the honeybee VIT are poorly understood. Objective Our aim was to evaluate risk factors for SRs during the build‐up phase of honeybee venom immunotherapy. Methods We included 93 patients who underwent ultra‐rush honeybee VIT. The adverse SRs and their severity was compared to various immunological (sIgE, tIgE, basophil CD63 response, baseline tryptase, and skin tests), patient‐specific (age, sex, cardiovascular conditions and medications, and other allergic diseases), and sting‐specific factors (anaphylaxis severity, time interval to onset of symptoms, and absence of cutaneous symptoms). Results Twenty‐three patients (24.7%) experienced mild SRs and 13 patients (14%) severe SRs. In five patients with severe SRs, the build‐up was stopped. High basophil allergen sensitivity, evaluated as dose–response curve metrics of EC15, EC50, CD‐sens, AUC, or the response to submaximal 0.01 μg/mL of venom concentration, was the most significant risk factor and only independent predictor of severe SRs and/or build‐up stop. Time interval of